For cardio it's irrelevant what you do, just that you do *something*.
If you prefer to do different types of exercise, then do. If you prefer to do the same one, then do. Just make sure that, either way, you challenge yourself so that you're continuously improving. That's enough 'variety' for your body.
You really should start Strength Training though. There's no need to wait. ST will help you to lose more fat. :)